1. Field of the Invention
The invention relates to new compositions and lubricating oils containing same. In particular, it relates to borated derivatives of hydroxyl-containing acid esters and their use in lubricating oils to reduce friction and fuel consumption in internal combustion engines.
2. Discussion of the Prior Art
So far as is known, no effort has been made to employ borated hydroxyl-containing acid esters as a lubricant additive or in sufficient amounts that it contributes to the lubricating properties of the blend. U.S. Pat. No. 2,788,326 discloses some of the esters suitable for the present invention, e.g. glycerol monooleate, as minor components of lubricating oil compositions. U.S. Pat. No. 3,235,498 discloses, among others, the same ester as just mentioned, as an additive to other oils. U.S. Pat. No. 2,443,578 teaches esters wherein the free hydroxyl is found in the acid portion, as for example in tartaric acid.
The above patents, as are numerous others, are directed to the use of such esters as additives. Other patents, such as U.S. Pat. Nos. 2,798,083; 2,820,014; 3,115,519; 3,282,971; and 3,309,318 as well as an article by R. S. Barnes et al. entitled "Synthetic Ester Lubricants" in Lubrication Engineering, August, 1957, pp. 454-457, teach lubricants prepared from polyhydric alcohols and acid containing no hydroxyl other than those associated with the acid function. However, all these references teach lubricants prepared from the fully esterified material.
In addition to the references already mentioned, the following patents are also of interest. U.S. Pat. No. 2,469,370 concerns boration of esters obtained from mono- or dihydric alcohols and fatty acids. U.S. Pat. No. 3,067,192 teaches borated acylated derivatives of polysaccharides. U.S. Pat. No. 3,150,157 relates to borated mono-acylated esters. U.S. Pat. No. 3,544,614 is concerned with complex esters for use in lubricants, the esters, in one aspect, being prepared by reacting boric acid, a polyhydric alcohol and a dicarboxylic acid or anhydride. U.S. Pat. Nos. 3,533,945 and 3,772,357 does relate to borated esters, the former teaching the ester to be one made by reacting a succinic acid-producing compound and a di- or polyhydric alcohol. The latter patent discloses, as prior art, the compound ##STR1##